Nov. 15, 1999 (Minneapolis) -- New research provides powerful data for women facing breast cancer surgery: The timing of surgery within the menstrual cycle can significantly effect long-term survival. A study by British researchers shows that women with breast cancer who are still menstruating, or are premenopausal, have significantly better chances of surviving the disease when surgery is performed before day three or after day 12 of their menstrual cycle. The findings were reported in the November issue of the journal Cancer.
While researchers have debated the issue of timing for breast cancer surgery for many years, this study may help resolve the controversy. "There is mounting evidence that the timing of surgery within the menstrual cycle has a significant effect on prognosis in premenopausal women with breast [cancer]," according to Ian S. Fentiman, MD and colleagues of Hedley Atkins Breast Hospital at Guy's Hospital in London.
The study looked at over 100 premenopausal women with operable breast cancer. For each woman, the point in the menstrual cycle on the day of surgery was determined beforehand. The women underwent one of two surgical procedures: breast conservation therapy or modified mastectomy. They were monitored over 10 years.
The results of the study revealed that timing of surgery within the menstrual cycle did affect survival. During the luteal phase, which typically occurs during the last two weeks of a woman's menstrual cycle, researchers found the patients' overall 10-year survival rate following surgery was 75%. But when surgery was performed during the follicular phase, between day three and 12 of the menstrual cycle, her 10-year rate of survival was only 45%.
Another important factor that influenced survival, according to the researchers, was whether or not the women's estrogen receptors (ER) and progesterone receptors (PR) were positive or negative. Hormones, particularly estrogen, play a significant role in breast cancer prognosis. The timing of the surgery, combined with the nature of the hormone receptors -- the sites on the cell's surface that binds with the hormones -- helped the scientists to determine which women would have the best overall survival rates.
The best-documented results were for those patients with ER-positive tumors who underwent surgery during the luteal phase. For these women, the 10-year survival rate was 80%. Although ER-positive and PR-positive tumors are less aggressive, even women with ER- or PR-negative tumors removed during the luteal phase of their menstrual cycle fared better than patients whose tumors were removed during the follicular phase.
"The results of this study reinforce the importance of the timing of surgery in the prognosis of premenopausal women with operable breast [cancer]," the researchers write. "These findings have not solved the mystery of the mechanisms involved in the timing of surgery. Nevertheless, they may influence patient management by rescheduling surgery, leading to a better prognosis."
Breast cancer is the most common cancer among women and the second most deadly. The American Cancer Society (ACS) estimates that 175,000 women will be diagnosed with invasive breast cancer -- that is, cancer that has spread to other tissues, and more than 43,000 will die from the disease in 1999. Early detection of breast cancer increases treatment options and survival. The ACS recommends annual mammograms, annual clinical exams, and monthly breast self-examinations for women age 40 years and older.